Reciprocating cross-head compressors



Oct. 18, 1960 J. R. MUNCK AF ROSENSCHOLD ETAL RECIPROCATING CROSS-HEAD COMPRESSORS 2 Sheets-Sheet 1 I Filed Dec. 10 1957 F ig.

J. R. MUNCK AF ROSENSCHOLD ETAL RECIPROCATING CROSS-HEAD COMPRESSORS Filed Dec. 10, 1957 2 Sheets-Sheet 2 United States Patent RECIPROCATING CROSS-HEAD COMPRESSORS John Rutger Munck af Rosenschiild, Saltsjobaden, and

Martin Waldemar Danielson, Johanneshov, Sweden, assignors to Atlas Copco Aktiebolag, Nacka, Sweden, a corporation of Sweden Filed Dec. 10, 1957, Ser. No. 701,837

Claims. (Cl. 230-188) This invention relates to reciprocating cross-head compressors with one or more cylinders and operating with single, two-stage or multiple-stage compression. In compressors of this type which are usually designed for medium or large output it is desirable to reduce the dimensions and weight'of the compressors and to adapt the design for operation by means of comparatively highspeed engines or electric motors. One object of the in vention is to reduce the construction height of the compressor and simultaneously the weight. Another object is to facilitate manufacture and assembly of the compressor and to reduce the cost. A still further object is to provide a construction which is simple in manufacture and avoids complicated castings.

In the accompanying drawings one embodiment of a two-cylinder two-stage reciprocating compressor embodying the invention is illustrated by way of example. Fig. 1 is a vertical cross section through a compressor according to the invention. Fig. 2 is a partial longitudinal section and side elevation of the compressor shown in Fig. 1. Fig. 3 is a detail section of the connection between the piston rod and the piston on a larger scale than shown in Fig. 1.

The compressor illustrated in the drawings consists of a crank case 1 which is provided with ribs 2 in conventional manner and an inspection opening 3 closed by a removable cover 4. A crank shaft 5 is rotatably mounted in the crank case 1. The crank case 1 is made integral with a throat 6 for a low-pressure cylinder and a throat 7 for a high-pressure cylinder. The throat 6 has an internal flange 8 which forms a seat 9 for a cross head guide 10 which comprises a ribbed tubular member arranged perpendicular to the plane of the seat 9 and provided with an external flange 11 substantially half way between the ends of the guide and formed to fit the seat 9 on the flange 8 in the crank case throat 6. The throat 6 is provided with a further external flange 12 of larger diameter than the flange 8 forming a seat 13 for a cylinder construction. The cylinder construction consists of a cylinder casing 14 provided with conventional cooling water jackets 15 and passages 16 for the air and an upper cylinder head 17 and a lower cylinder head or cover 18. Suction valves 19 and discharge valves 20 are provided in suitable ports in the cylinder head 17 and the lower portion of the cylinder casing 16. Numeral 21 indicates the air intake opening to the cylinder 14 and 22 the discharge opening from which the compressed air is conveyed through an intercooler (not illustrated) to the high-pressure cylinder.

A cross head 23 is reciprocable in the cross head guide 10 and connected to the crank shaft 5 by means of a connecting rod 24. A piston rod 25 connects the cross head 23 with a piston 26 which is reciprocable in the compressor cylinder. The single-wall lower head or cover 18 has a flange 27 which together with the cylinder casing 16 is bolted on to the seat 13 on the flange 12 by means of bolts 28. The arrangement of the cross head guide and lower cylinder cover gives a low and inexpen- The high-pressure cylinder is arranged in substantially the same way as the low-pressure cylinder construction and consists of a cylinder casing 29, a cylinder head- 30 and an inner cylinder head or cover 31. The only difference is that the cylinder casing 29 is bolted directly to an external flange 32 on the throat 7 by means of bolts 33 whereas the inner head or cover 31 has a flange 34 which is bolted to the cylinder casing 29 by means of bolts 35. Other parts of the high-pressure cylinder construction are designated by the same reference numerals as those used in connection with the low-pressure cylinder and are similar to those of the low-pressure cylinder construction and are not described in detail.

The piston rod 25 is provided with two accurately machined portions 36 and 37 which fit in corresponding bores 38 and 39 in the piston 26. An intermediate portion 40 of the piston rod 25 is screw threaded and engages corresponding screw threads 41 in the piston. A washer 42 is counter-sunk in the piston. to accommodate a screw threaded tension bolt 43 which is secured in the piston rod by a screw threaded portionhas been loosened the piston 26 may be rotated by a suit-' able tool engaging bores 45 to move axially on the rod 25 and after having been placed in proper position the piston is locked to the piston rod by tightening the bolt 43 with so much force that the tension of the bolt 43 is sufli-,

cient to overcome the forces set up in the joint between the piston rod and the piston during reciprocation of the piston. The length of the portion 46 of the bolt extending freely through the rod 25 is calculated for forming a suitable elastic means for safely holding the piston down on the piston rod without permitting the piston to loosen during operation.

It is obvious to those skilled in the art that various modifications of the illustrated compressor are possible within the scope of the claims and the illustrated compressor is only shown as an example. The invention may for instance be employed in single or multiple cylinder compressors as well as in single or multiple stage compressors. The joint between the piston and piston rod may be used to connect the piston rod and the crosshead also and in compressors or reciprocating engines of any type.

What we claim is:

1. A reciprocating cross head compressor comprising a crank case, a main crank shaft rotatably mounted in said crank case, a throat formed by said crank case integral therewith and perpendicular to the axis of rotation of said crank shaft, a first annular seat inside said throat disposed in a plane parallel to said axis of rotation, a separate tubular cross head guide mounted on said first seat, a cross head reciprocable in said guide in a direction perpendicular to said first seat, a connecting rod connecting said crank shaft to said cross head, a second annular seat of larger diameter than said first seat at the free end of the throat in a plane parallel to the plane of said first seat, a compressor cylinder construction having valved intake and discharge ports mounted on said second seat, and -a piston and piston rod connected to said cross head and reciproca-ble in said cylinder construction.

2. A reciprocating cross head compressor comprising a crank case, a main crank shaft rotatably mounted in said crank case, a throat formed by said crank case integral therewith, a first seat inside said throat, a cross head guide mounted on said first seat, a cross head reciprocable in said guide, a connecting rod connecting said crank shaft to said cross head, a second sea-t at the free The piston rodis boredend of the throat, a compressor cylinder construction having valved intake and discharge ports mounted on said second seat, a double acting piston and piston rod connected to, said cross head and reciprocable in said cylinder construction, and a cup shaped single wall cylinder head at the crank case end of said cylinder construction extending into said crank case end of the cylinder.

3. A reciprocable cross head compressor comprising a crank case, a main crank shaft rotatably mounted in said crank case, a first seat on said crank case, a tubular cross head guide having an external flange at an intermediate portion between the ends of the guide and mounted with said flange on said first seat, a cross head reciprocable in said guide, a connecting rod connecting said crank shaft to said cross head, a second seat of larger diameter than said first seat on the crank case, a compressor cylinder construction having valved intake and discharge ports and an end plane on the crank case end and mounted with said end plane on said second seat, and a piston and piston rod connected to said cross head and reciprocable in, said cylinder construction.

4. A reciprocating cross head compressor comprising a crank case, a main crank shaft rotatably mounted in said crank case, a first seat on said crank case disposed in a plane parallel to the axis of rotation of said crank shaft, 3. cross head guide mounted on said first seat, a cross head reciprocable in said guide in a direction perpendicular to the first seat, a connecting rod connecting said crank shaft to said cross head, a second seat on the crank case of larger diameter than said first seat and ofiset from the crank case relative to the first seat and disposed in a plane parallel to the plane of said first seat, a compressor cylinder construction having valved discharge ports and an end plane at the crank case end and mounted with said end plane on said second seat, and a piston rod connected to said cross head and reciprocable in said cylinder construction.

S. A reciprocating cross head compressor comprising a crank case, a main crank shaft rotatably mounted in said crank case, a separate cross head guide mounted on said crank case, a cross head reciprocable in said guide, a connecting rod connecting said crank shaft to said cross head, a compressor cylinder construction having valved intake and discharge ports and jackets for water cooling the cylinder, said jackets extending around the periphery of the cylinder and along its length to the crank case end thereof, and a double acting piston and piston rod connected to said cross head and reciprocable in said cylinder construction, said cylinder construction comprising a cylinder casing, a valved head at the free end of the cylinder, and a cup-shaped single wall cylinder head or cover at the crank case end of the cylinder construction extending into said crank case end of the cylinder and deriving its cooling through conduction from the jacketed crank case end of the cylinder construction.

References Cited in the file of this patent UNITED STATES PATENTS 

